Conventionally, known is a battery pack having a rechargeable battery in which temperature fuses are connected to the rechargeable battery in series. When this kind of battery pack detects an abnormality of the rechargeable battery, it causes a heater to generate heat based on the output voltage of the rechargeable battery to melt the temperature fuses so that the battery pack can no longer be used on a permanent basis.
Nevertheless, if the battery voltage of the rechargeable battery is low, there are cases where the amount of heat generated by the heater is insufficient even if the battery voltage is applied to the heater, whereby the temperature fuses will not melt. In the foregoing case, in addition to the temperature fuses not melting, there is also a drawback in that the heater within the battery pack will continue to generate heat and cause the temperature of the battery pack to increase.
Thus, known is technology for causing the heater to generate heat and melt the temperature fuses by waiting for the rechargeable battery to be charged so that the battery voltage reaches a predetermined voltage in cases where the battery voltage of the rechargeable battery is less than a predetermined voltage capable of melting the temperature fuses (for example, refer to Patent Document 1).
Meanwhile, if there is any abnormality which may melt the fuses, from the perspective of safety, it is desirable to melt the fuses without discharging the rechargeable battery as much as possible. This is because, when discharging the rechargeable battery and using its power to melt the fuses, the temperature of the rechargeable battery will further rise due to the discharge.
Nevertheless, since the technology described in Patent Document 1 melts the temperature fuses by discharging the rechargeable battery when there is an abnormality that may melt the fuses, there is a drawback in that this is undesirable from the perspective of safety.
Patent Document 1: Japanese Patent Application Publication No. 2007-215310